To hear House Speaker John Boehner tell it, President Obama is a veritable Stephen Colbert.

“It’s clear that the president’s just not serious,” Boehner said at his weekly news conference in the House TV studio Thursday.

“The White House is so unserious,” he said a moment later.

“Here we are at the 11th hour, and the president still isn’t serious,” he repeated.

Boehner is right — seriously. The administration hasn’t been treating the “fiscal cliff” talks as a substantial negotiation, and for one very good reason: It’s not clear it has anybody to negotiate with.

At the White House and on Capitol Hill, a fear is growing that Boehner is not in a position to negotiate a successful deal, because if he strikes the kind of compromise needed to solve the fiscal standoff, he may well lose the support of his House GOP caucus — and possibly his job as speaker.

“Mr. Speaker,” PBS’s Linda Scott asked him after his accusations that Obama is unserious, “could you describe how difficult it is to craft a deal that your conference will support while not jeopardizing your job as speaker?”

“I’m not concerned about my job as speaker,” Boehner said.

Seriously?

Herein lies the danger in the fiscal negotiations and the reason a deal may have to wait until after Jan. 1. In negotiating with Boehner, the White House is up against what might be called an irrational-actor problem.

Boehner himself surely wants a deal. But while he is the titular leader of House Republicans, he is at the mercy of backbenchers who have a fanatical opposition to tax increases.

A top negotiator for the administration said privately week that he now expects the government to go over the fiscal cliff, because the ensuing panic may be the only thing that will allow Boehner to gain the leverage he needs in his “Lord of the Flies” caucus. But that notion — risking recession to increase Boehner’s bargaining position within his own caucus — is the riskiest of gambles.

Neither side has made much of a substantial offer to avoid the cliff. The White House has avoided major concessions because officials know they have the winning political hand: Republicans will likely be blamed for the disaster. And Boehner has avoided most specifics because his offer would be picked apart by many on his own side. Though Republicans have essentially conceded that taxes on the wealthy will rise, they haven’t agreed how.

Congressional Democrats, for their part, are contributing to negotiations largely by taunting Boehner over his weakness.

“Speaker Boehner can’t ignore the American people forever,” Senate Majority Leader Harry Reid said at his own news conference, after Boehner’s.

“The obvious question the American people are asking, and we’re asking is, ‘What is John Boehner waiting for?’ ” Dick Durbin of Illinois, the No. 2 Senate Democrat, added. “Is he waiting for Jan. 3, his election as speaker? I hope it’s not that.”

Boehner, trying to keep the focus on Obama, showed up for the media Thursday with a new visual aid: a multicolor chart, courtesy of Paul Ryan, and a Twitter hashtag, #spendingistheproblem.

Boehner beckoned to his handsome graphic: “The president still isn’t serious about dealing with this issue right here,” he said, with a gesture toward the chart’s climbing blob of red that represented future government spending.

But the speaker was having trouble shifting the focus to the White House. Fox News’s Chad Pergram asked Boehner why he again found himself up against a year-end deadline and another last-minute struggle. “Is there a systemic problem of Congress?” he asked.

“Unfortunately, that is the case that we’re dealing with today,” Boehner allowed.

In this case, though, there is a simple way out: Boehner can agree to the White House demand to increase taxes on the top 2 percent of earners, then work out a second deal on spending and tax reform. The president would still be under pressure to negotiate because the tax increase on the wealthy wouldn’t do much to improve revenue. But allowing that vote could cause a mutiny among House Republicans.

Andy Taylor of the Associated Press asked if there was any chance he’d allow such a vote. The speaker offered his standard demurral: If ifs and buts were candy and nuts, “every day would be Christmas.”